
if(document.body.classList == null && Element){
	var wjClassList = { 
		el: null,
		names: [],
		getClass: function(){
			var cNames = this.el.className;
            this.names = cNames ? cNames.trim().split(/\s+/) : [];
		},
		genClass: function(){
	         this.el.className = this.names.join(" ");
	    },
		add:function(cName){
	        var i = this.contains(cName);
	        if(i === false){
	            this.names.push(cName);
	            this.genClass();
	        }
	    },
	    remove: function(cName){
            var i = this.contains(cName);
            if(typeof i == "number"){
                this.names[i] = "";
                this.genClass();
            }
      	},
	    toggle: function(cName){
            var i = this.contains(cName);
            if(i === false){
                this.add(cName);
            }else{
                this.remove(cName);
            }
		},
        contains: function(cName){
        	this.getClass();
        	
            var i, len = this.names.length;
            for(i = 0; i < len; i++){
                if(this.names[i] == cName){
                    return i;		// 如果存在，返回索引
                }
            }
            return false;
       },
	};
      
      
    // 在不支持classList的浏览器中, 在Element的原型中写入此方法
	Object.defineProperty(Element.prototype, 'classList', {
		get: function(){
			wjClassList.el = this;
			return wjClassList;
		}
	});
}
